It is known that with program-controlled radio receivers it is possible to search for the transmit frequency with the best reception at the given location.
The reception quality of a transmit frequency is known to depend on the distance between the location of the transmitter and that of the receiver. If this distance is increased, transmitter reception quality may be lost.
If various transmit frequencies stored in a radio receiver can be activated by freely selecting one via the actuator, then it is also beneficial to know whether the distance between the transmitter and receiver has changed significantly between two successive operating times at the same transmit frequency, i.e., whether there has been a significant change in location of the receiver in the meantime. Frequent and significant changes in location can be expected with car radios in particular.